JP2000047493A - Separating claw for electrophotographic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a separating claw for electrophotographic device with sharp tip improved in wear resistance, non-adhesive property to toner and durability. SOLUTION: A mixture obtained by mixing polyimide resin powder with polytetrafluoroethylene resin powder having a weight average molecular weight of 500,000-1,000,000 and an average grain size of 5-20 μm in a ratio of 70:30-95:5 on the basis of weight is compression molded and baked to form this separating claw.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a separation claw used in an electrophotographic apparatus such as a copying machine and a laser beam printer, and more particularly, to a paper jam having a sharp tip and fusing toner. The present invention relates to a separation claw which has a significantly improved durability and can prevent the separation claw for a long time.

[0002]

2. Description of the Related Art Conventionally, there has been developed a separation claw for preventing the occurrence of paper jam due to fusing of toner or the like.

[0003] Separation claws in which at least a portion of the tip of the separation claw formed of a polyimide resin, which is in contact with the copy paper, is coated with a tetrafluoroethylene-perfluoroalkylvinyl ether co-weight (JP-A-1-72182), a fluororesin primer There is a separation claw molded from a polyamide-imide resin or a polyphenylene sulfide resin having a multilayer coating film composed of a layer and a top layer.

[0004] In addition to the technique of coating the surface of the separation claw with a fluororesin, polyimide resins 40 to 90
Separation claws for copiers obtained by compression molding and baking a blend of 60 to 10% by weight of a fluorine-based resin such as a polytetrafluoroethylene resin.
No. 83) or a mixture of 30 to 90% by weight of a polyimide resin and 70 to 10% by weight of a tetrafluoroethylene-perfluoroalkylvinyl ether co-weight, and the inscribed circle diameter at the tip of the nail is 70 μm or less. A separation claw (JP-A-6-19360) formed by forming a separation claw green compact having a certain shape and then firing the same has been developed.

[0005]

However, as the quality and life of electrophotographic devices such as copiers and the like have been improved, and the recent tendency to use recycled paper, the separation claw has no adhesion to toner. It is desired to improve the resilience, the abrasion resistance to withstand rubbing by toner or paper dust, and minimize the diameter of the separation claw tip.

Accordingly, an object of the present invention is to solve the above-mentioned problems and to provide a separation claw for an electrophotographic apparatus having a sharp tip with improved abrasion resistance, non-adhesion to toner, and durability.

[0007]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve such problems, and as a result, have found that powders of polytetrafluoroethylene resin having a weight-average molecular weight and an average particle size within a certain range are obtained. It has been found that a separation claw having improved abrasion resistance and non-adhesiveness to toner can be provided by using a blend with the polyimide resin powder.

In order to solve the above-mentioned problems, a separation claw for an electrophotographic apparatus according to the present invention comprises a polyimide resin powder and a polytetrafluorocarbon having a weight average molecular weight of 500,000 to 1,000,000 and an average particle diameter of 5 to 20 μm. It is characterized by being obtained by compression-molding a blend obtained by blending ethylene resin powder at a ratio of 70:30 to 90: 5 based on weight, and then firing.

[0009] Another separation claw according to the present invention is the separation claw described above, wherein the tip diameter of the separation claw is 50 µm or less.

[0010] Still another separation claw according to the present invention is:
Any of the above separation nails, wherein the water repellent angle of the surface of the separation nail is 100 degrees or more, and the water repellency angle of the surface is 90 degrees or more even if the surface of the separation nail is worn down to 50 μm. Features.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The polyimide resin powder used in the present invention comprises pyromellitic dianhydride, 3,3 ',
One or more acids selected from the group consisting of 4,4'-biphenyltetracarboxylic dianhydride and 3,3 ', 4,4'-benzophenonetetracarponic dianhydride;
And polycondensates or copolymers with one or more diamines selected from the group consisting of 4,4'-diaminodiphenyl ether, 1,3-phenylenediamine, and 1,4-phenylenediamine. Heat deformation temperature is 340 ℃
Since the above is very high and the balance between strength and elongation is good, a polycondensate of 4,4'-diaminodiphenyl ether and pyromellitic dianhydride and 3,3 ', 4,4'
Polyimide resin powder which is a copolymer of -biphenyltetracarboxylic dianhydride, 1,3-phenylenediamine and 1,4-phenylenediamine is preferred, and 4,4'-
Polycondensates of diaminodiphenyl ether and pyromellitic dianhydride are particularly preferred.

The polytetrafluoroethylene resin powder used in the present invention has a weight average molecular weight of 500,000 to 500,000.
1,000,000 and an average particle size of 5 to 20 μm. Since polytetrafluoroethylene resin has a high melting point, it can sufficiently withstand the firing temperature of any of the above polyimide resin powders, but there is a problem that other conventionally known fluororesins are decomposed by firing the polyimide resin powder. .

The weight average molecular weight of the polytetrafluoroethylene resin powder is preferably from 600,000 to 800,000, more preferably from 600,000 to 700,000. The average particle size is preferably 5 to 15 μm, and 7 to 12 μm.
m is more preferred. 500,000 weight average molecular weight
If it is smaller, it will thermally decompose at the firing temperature of the polyimide resin,
Unevenness occurs on the surface of the separation claw. On the other hand, if the weight average molecular weight is more than 1,000,000, the melting temperature is extremely high, and when the polyimide resin is melted at the sintering temperature, it becomes difficult to flow, so that the spread of the separation nail to the surface is insufficient. Also, if the average particle size is smaller than 5 μm or larger than 20 μm, the dispersibility is poor and a separation nail having a good surface cannot be obtained.

The compounding ratio of the polyimide resin powder and the polytetrafluoroethylene resin powder is 70:
30-95: 5. Preferably, 80: 20-9
0:10, and more preferably 85:15. If the blending ratio of the polytetrafluoroethylene resin powder is less than 5, the non-adhesiveness to the toner is insufficient, while if the blending ratio is more than 30, the tip strength of the separation claw is too low.

In the present invention, graphite may be added to the polyimide resin powder together with the polytetrafluoroethylene resin powder as long as the performance of the separation nail is not affected.

The separation nail of the present invention comprises a polyimide resin powder and a weight average molecular weight of 500,000 to 1,000,000.
0, a polytetrafluoroethylene resin powder having an average particle diameter of 5 to 20 μm, and 70:30 to 95: 5 based on weight.
And compression-molding the resulting mixture, followed by firing. The blend of the polyimide resin powder and the polytetrafluoroethylene resin powder is a dry blend. It must be compounded under conditions that do not place an excessive load on the polyimide resin powder. The compression molding is usually performed at a compression surface pressure of 40,000 psi or more, and the calcination is usually performed at a temperature of 380 ° C. to 500 ° C. for 4 hours or more, resulting in substantially complete conversion of the polymer to polyimide. . It is preferable that the surface of the separation nail is made smoother by washing after baking and barrel polishing.

The separation claw of the present invention preferably has a tip diameter of 50 μm or less, more preferably 30 μm or less. If the separation claw made of polyimide resin is coated with fluororesin, it is very difficult to reduce the tip diameter of the separation claw to 50 μm or less,
In the present invention, since no coating is performed, the accuracy of the molded product is easily obtained.

In the present invention, the water repellency angle of the surface of the separation nail is used as an index indicating the non-adhesion of the surface of the separation nail to the toner. The water repellency angle was determined by dropping about 0.4 μl of distilled water on the surface of the separation nail with an injection needle and using an image processing contact angle meter (CA-X150, manufactured by Kyowa Interface Science Co., Ltd.). Is a value obtained by measuring.

Polyimide resin powder and weight average molecular weight 5
00,000-1,000,000, average particle size 5-20
The surface of the separation nail obtained by compression-molding a compound obtained by mixing a polytetrafluoroethylene resin powder with a μm polytetrafluoroethylene resin powder in a ratio of 70:30 to 95: 5 based on the weight, and then firing. Has a water repellent angle of 100 degrees or more, and even if the separation nail surface is worn down to 50 μm, the water repellent angle of the surface is 9 degrees.
It is maintained at 0 degrees or more. When the surface of the separation nail is coated with a fluororesin, its film thickness is 30 to 50.
μm. On the other hand, in the separation nail of the present invention,
Without coating, not only does the separation nail surface have non-adhesiveness to the toner, it can also maintain non-adhesion to the toner even if the surface layer is worn, and it is more durable than the coated separation nail. I have.

[0020]

EXAMPLES The present invention will be described with reference to examples, but the present invention is not limited to these examples.

(Examples 1-2, Comparative Examples 1-4, Control Example 1) Polyimide resin powder which is a polycondensate of 4,4'-diaminodiphenyl ether and pyromellitic dianhydride (Vespel (DuPont) (Registered trademark) SP-1) and a polytetrafluoroethylene resin powder having a weight-average molecular weight and an average particle size shown in Table 1 based on a weight of 9
The mixture was dry-blended at a ratio of 0:10, filled in a mold for a separation nail, compressed at a compression surface pressure of 40,000 psi or more, and baked at a temperature of 380 to 500 ° C. for 4 hours or more.
After firing, cleaning, barrel polishing, tip diameter about 30μ
m separation nails were prepared.

Further, as Comparative Example 1, separation nails were prepared using only the same polyimide resin powder under the same manufacturing conditions.

The surface of the obtained separation nail was visually observed. Table 1 shows the results.

[0024]

[Table 1]

When Examples 1 and 2 are compared with Comparative Example 1, if the weight average molecular weight and the average particle size of the polytetrafluoroethylene powder are out of the range of the present invention, it is possible to obtain a separation nail having a smooth surface. It turns out that you can't.

When Examples 1-2 and Comparative Examples 2-4 are compared, even if the average particle size of the polytetrafluoroethylene powder is within the range of the present invention, the weight-average molecular weight is out of the range of the present invention. If it is off, it can be seen that the dispersibility of the polytetrafluoroethylene resin powder is poor and a separation nail having a smooth surface cannot be obtained.

(Examples 3 to 6) A polyimide resin powder (Vespel (registered trademark) SP-1 manufactured by DuPont), which is a polycondensate of 4,4'-diaminodiphenyl ether and pyromellitic dianhydride, and a weight Average molecular weight 600,000
７００700,000 and polytetrafluoroethylene resin powder having an average particle size of 7 to 12 μm were dry blended at a blending ratio based on the weight shown in Table 2 and filled in a mold for a separation claw. Compress at 000 psi or higher, temperature 3
It was calcined at 80 ° C to 500 ° C for 4 hours or more. After baking, it was washed and barrel polished to form a separation claw having a tip diameter of about 30 μm. The tip strength of the obtained separation nail and the separation nail of Comparative Example 1 was measured. Specifically, the separation claw is fixed to the base so that the paper passing surface is perpendicular to the base of the compression tester, and a load is applied to the claw tip with a flat plate from above vertically, and when the tip breakage occurs Was measured to determine the tip strength. Table 2 shows the results.

[0028]

[Table 2]

When Examples 3 to 6 and Comparative Example 1 are compared,
It can be seen that the greater the blending amount of the polytetrafluoroethylene resin powder, the lower the tip strength both at room temperature and in a high-temperature atmosphere.

(Example 7, Comparative Examples 5 to 6) Polyimide resin powder which is a polycondensate of 4,4'-diaminodiphenyl ether and pyromellitic dianhydride (Vespel (registered trademark) SP-1 manufactured by DuPont) ) And a weight average molecular weight of 60
A polytetrafluoroethylene resin powder having an average particle diameter of 7 to 12 μm and
Dry blending at a compounding ratio of ??, filling in a mold for a separation nail, and compressing at a compression surface pressure of 40,000 psi or more, at a temperature of 3
It was calcined at 80 ° C to 500 ° C for 4 hours or more. After baking, washing and barrel polishing were performed to form a separation claw having a tip diameter of about 30 μm. About 0.4 ml of distilled water was dropped on the surface of the obtained separation nail with an injection needle, and an image processing contact angle meter (CA-X150 manufactured by Kyowa Interface Science Co., Ltd.) was used.
The contact angle was measured using a mold) to determine the water-repellent angle.
Further, the surface is 50 μm with a 1000 mesh water-resistant abrasive paper.
After polishing, the contact angle with water was measured in the same manner to determine the water repellent angle.

A polyimide resin powder (Vespel (registered trademark) SP manufactured by DuPont), which is a polycondensate of 4,4'-diaminodiphenyl ether and romellitic dianhydride, is also available.
-1) was charged into a mold of a separation claw, and the compression surface pressure was 40,00.
Compressed at 0 psi or more and fired at a temperature of 380 ° C. to 500 ° C. for 4 hours or more. After baking, it was washed and barrel polished. The water repellent angle on the surface of the obtained separation nail was measured in the same manner as Comparative Example 5.

A primer of a tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer was applied to the surface of the separation nail prepared in the same manner as in Comparative Example 5 and dried, and the top of the tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer was further dried. After spray-coating a coat dispersion (average particle size 0.2 to 0.4 μm), baking,
A coating layer having an average thickness of the primer layer of 10 μm and an average thickness of the top layer of 20 μm was formed.

The water repellent angle on the surface of the obtained separation nail was measured in the same manner. Further, in the same manner as in Example 7, the surface was polished with a 1000-mesh water-resistant abrasive paper by 50 μm, and then the water repellency angle was measured.

The water repellency angle was measured three times, and the average was determined. Table 3 shows the results.

[0035]

[Table 3]

Comparing Example 7 with Comparative Example 5, it can be seen that the water repellency of the surface of the separation nail is increased by blending the polytetrafluoroethylene resin powder. From this, it can be considered that the non-adhesiveness to the toner is improved.

Comparing Example 7 with Comparative Example 6, it can be seen that the surface of the separation claw of the present invention has the same non-adhesiveness to the toner as when coated with a fluororesin. Even when the surface is polished to 50 μm, the separation claw of the present invention can maintain excellent non-adhesiveness. However, in the case of a separation claw coated with a fluororesin, no matter how thick the coating is, the film thickness is no more than 50 μm. It can be seen that the degree of non-adhesion is reduced because of the degree.

(Embodiment 8) The separation claw of Embodiment 1 was attached to a commercially available medium-speed copying machine, and a paper passing test of A4 size copy paper was performed at a speed of 30 sheets / min. Defects such as toner adhesion and tip abrasion did not occur even after separation. Further, no damage was caused to the fixing roll portion to be brought into contact.

[0039]

As described above, according to the present invention, it is possible to manufacture a separation claw for an electrophotographic apparatus having a sharp tip with improved abrasion resistance and non-adhesion to toner without coating with a fluororesin. Can be. Further, the separation claw of the present invention is a separation claw excellent in durability that can maintain non-adhesiveness even when its surface is worn.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Akira Yokoyama 19-2 Kiyohara Industrial Park in Utsunomiya City, Tochigi Prefecture Dupont Co., Ltd. (72) Inventor Shinichi Nakagawa 19-2 Kiyohara Industrial Park in Utsunomiya City, Tochigi Prefecture F-term in Central Technology Research Laboratories, Inc. (Reference) 2H032 DA12 DA17 2H033 AA16 AA23 BA16 BA19 BA20 4J002 BD152 CM041 GP00 GT00 HA09

Claims (3)

[Claims] 1. A separation claw for an electrophotographic apparatus obtained by compression-molding a mixture of a polyimide resin powder and a polytetrafluoroethylene resin powder and then firing the mixture, wherein the polyimide resin powder and the polytetrafluoroethylene resin powder Is 70:30 to 95: 5, and the polytetrafluoroethylene resin powder has a weight average molecular weight of 500,000 to 1,000,000 and an average particle size of 5 to 20 μm. The separation claw characterized by the above. 2. The separation claw according to claim 1, wherein a tip diameter of the separation claw is 50 μm or less. 3. The water repellent angle of the surface of the separation claw is 100 degrees or more, and even if the surface of the separation claw is worn down to 50 μm, the water repellency angle of the surface is 90 degrees or more. Item 3. The separation nail according to Item 1 or 2.